The present invention relates to peripheral memory storage devices for computers, and more particularly, to transports that provide the mechanical functions required to store and retrieve digital data from magnetic tape.
Most personal computer systems have Winchester disk drives that provide both substantial storage capacity and rapid data access. A popular Winchester disk drive has a five and one-quarter inch diameter rigid disk that can store forty megabytes or more of information. Archival back-up storage is desirable, yet backing up this type of hard disk drive with floppy diskettes is tedious. This is because the storage capacity of such "floppies" is relatively small and many must be loaded and unloaded in succession
For many years tape drives have been available for providing back-up storage for personal computers having Winchester disk drives. They permit the entire contents of the hard disk to be stored on a single tape cartridge of, for example, the type defined by ANSI X3.55-1977. See also U.S. Pat. No. 3,692,255. This type of cartridge has been sold in large numbers under the designations DC300 and DC600 by Minnesota Mining and Manufacturing Company. Both the DC300 and the DC600 are identical mechanically except for the length of tape. This type of tape cartridge is hereafter referred to as the "DC600-type" cartridge, which is presently the most widely used configuration. That cartridge measures six inches in length by four inches in width. It has a belt capstan roller which may be engaged by a capstan drive roller to propel a length of magnetic tape, either 300 feet or 600 feet, between a pair of reels inside a plastic housing. The cartridge further has a hinged tape access door which may be opened to expose the tape. The opening of this tape access door increases the width of the tape cartridge from four inches to five and three-quarter inches when the door is fully opened. Both the DC300 and the DC600 are identical mechanically except for the length of tape.
For many years both floppy disk drives and Winchester disk drives have been manufactured according to a de facto size standard which requires that they fit within a physical envelope (rectangular box) measuring three and one-quarter inches in height by five and three-quarter inches in width by eight inches in length. The aforementioned dimensions are known throughout the computer peripherals industry as the five and one-quarter inch form factor. This is a name derived from the diameter of the disk. Originally the DC600 type cartridge was designed to be loaded sideways into a tape transport sized to fit an earlier, larger form factor measuring eight inches in width. When the five and one-quarter inch Winchester disks first became popular it was believed that a tape drive could not be provided that would permit endwise loading of the DC600-type tape cartridge into the same form factor. The term "endwise" refers to loading the cartridge so that the side edge with the tape access door and belt capstan roller is generally parallel to a longitudinal axis of the frame (eight inch dimension of the form factor).
Engineers at Cipher Data Products, Inc., the assignee of this application, were the first to invent a tape drive that would permit endwise loading of the DC600-type tape cartridge in the five and one-quarter inch form factor while still achieving the required cartridge registration, door opening, read/write head engagement, capstan drive roller engagement and track selection functions in a very confined space too small to permit full opening of the tape access door. See U.S. Pat. Nos. 4,573,091 and 4,677,508 of William M. Barton, Jr. et al. This endwise loading configuration has permitted backup tape drives to fit within the five and one-quarter inch receptacles in a wide variety of personal computers (PCs). This has enabled computer owners to continue using their large libraries of existing DC600-type cartridges. Several hundreds of millions of dollars worth of tape drives covered by the claims of the aforementioned patents have been sold by Cipher Data Products, Inc., Wangtek, Inc., Archive Corporation and others. Claims of the aforementioned U.S. Pat. Nos. 4,573,091 and 4,677,508 were found not invalid and were found to have been infringed by a jury verdict rendered on May 26, 1988 in the case of Cipher Data Products, Inc. v. Wangtek, Inc. (Civil Action No. 86-3792 EFL) in the United States District Court for the Northern District of California.
Disk drives have subsequently been developed and widely sold that fit the five and one-quarter inch form factor in width and length, but which only require one and five-eighths inches in height. Two of these so-called half-height drives can fit in the same five and one-quarter inch form factor. Half-height end loading tape drives for the DC600 type cartridge embodying the invention of U.S. Pat. Nos. 4,573,091 and 4,677,508 have also been sold in large numbers.
Initially, all commercially successful end loading tape drives for the DC600-type cartridge utilized manually actuated mechanisms for opening the tape access door and swinging the read/write head and capstan drive roller into engagement with the cartridge and for reversing the process to unload the cartridge. Two of the three most popular drives (Cipher and Archive) employ a load lever which must be slid back and forth to operate a head and capstan engaging linkage. A third one of the most popular drives (Wangtek) has utilized a so-called "push-push" spring loaded reciprocating tray mechanism which moves the head and capstan drive through a linkage. While such tape drives have in general been quite serviceable, they have required some degree of user familiarity to operate. Jams have occurred. In some cases the head can be engaged too rapidly, or even rammed into the cartridge housing. Cartridge ejection has generally been acceptable, although manual actuation has been required. Aside from the inconvenience of such manual loading, the principal drawback of such prior configurations has been that the head must be swung into and out of engagement with the tape. Since this requires that the head be supported for pivotal movement, it has been difficult to maintain the tolerances required for accurate reading and writing of data as the storage capacity of such drives has increased, bringing with it a requirement for increased numbers of tracks on the tape and increased recording densities (bits per inch).
U.S. Pat. No. 4,673,995 of Spiegelstein discloses a five and one-quarter inch form factor tape drive for end loading the DC600-type cartridge in which the cartridge is first end load during which the door is opened by a skewed friction roller. The cartridge is then manually pivoted laterally (in a horizontal plane) into engagement with a head. The head is fixed in the horizontal plane, but is vertically reciprocable for track selection. Cipher Data Products, Inc. has successfully commercialized an improved version of the Spiegelstein configuration denoted the ST150S/90 in which the cartridge is translated laterally in parallel with its end edges, instead of pivoting laterally about a point located rearward on the metal base plate of the cartridge. The lateral translation of the cartridge in this ST150S/90 drive is accomplished through manual sliding of a loader lever. The improved design of this drive has enabled the storage of approximately 150 megabytes of data on a single DC600 type cartridge. However, this drive still requires a degree of operator familiarity with the manual cartridge loading and unloading process.
U.S. Pat. No. 4,559,571 of Olmsted et al. discloses a full height, manually end loaded, five and one-quarter inch form factor tape drive for the DC-600 type cartridge. The insertion slot is sealed by manually closing hinged door 42. After the tape access door of the cartridge is opened the read/write head 30 is swung both vertically and laterally into engagement with the tape. This head movement is actuated by drive motor 66.
U.S. Pat. No. 4,636,890 of Rudi et al. discloses another five and one-quarter inch form factor drive for the DC-600 type cartridge in which the read/write head is swung into engagement through a linkage connected to the door that closes the cartridge insertion slot
U.S. Pat. No. 4,796,120 of Komatsu et al. discloses another half-height, end loading five and one-quarter inch form factor tape drive for the DC600-type cartridge. The cartridge is manually inserted endwise onto a cartridge guide plate 50, in a door-first orientation. The tape access door is opened and then a hinged door 20 on the front of the tape drive is manually swung up to close the cartridge insertion slot. At the same time, mechanisms connected to the door move the read/write head vertically and the cartridge laterally into engagement with the head.